1. Technical Field
The present invention relates to a method for separating two sheetings, more particularly to a method and an apparatus for separating two disc-shaped substrates from each other, which substrates form an optical disc.
2. Background
Optical discs such as digital video discs (hereinafter referred to as xe2x80x9cDVD""sxe2x80x9d) and the like have two disc substrates, wherein a signal is normally applied to only one of the disc substrates.
Notwithstanding, due to the necessity for increasing memory capacity, DVD""s having signals applied to both disc substrates have appeared on the market.
Under such circumstances, ways for further increasing memory capacity have been studied.
FIGS. 5A and 5B illustrate an example for increasing capacity, and show a production step of a so called DVD 9 optical disc.
FIG. 5A shows the production step in perspective. FIG. 5B shows the same production step in cross-section.
A mode for carrying out the present invention will be described below in detail. A disc-shaped substrate 100 (first disc-shaped substrate) which includes (polymethacyric acid methyl) PMMA used for trial and a disc-shaped substrate 200 (second disc-shaped substrate) are prepared (step 1).
A data logging display of the disc-shaped substrate 100 composed of PMMA is subjected to sputtering (for instance, metallic coatings such as aluminum and the like are formed thereon). In the same manner, the disc-shaped substrate 200 comprised of polycarbonate is also subjected to sputtering.
These two surfaces that are subjected to sputtering are put together and then laminated or fixed to one another by use of an adhesive R (Step 2).
In this instance, laminating is performed in such a manner that, for instance, two disc-shaped substrates are carried on a rotary table and rotated to develop, as a whole, the adhesive applied between the disc-shaped substrates (normally, UV resin) and then the adhesive is cured (normally this is done through radiation of ultraviolet rays).
In this manner, two disc-shaped substrates 100, 200 are laminated by an adhesive R to form an integrated unit.
Now, the disc-shaped substrates 100, 200 which form the integrated unit are separated from each other.
In other words, the first disc-shaped substrate 100 and the second disc-shaped substrate 200 are pulled apart (Step 3).
In this instance, PMMA, which comprises the first disc-shaped substrate 100, has difficulty adhering to the other material. A portion 101 which has been subjected to sputtering is separated from the PMMA wherein it adheres to the second disc-shaped substrate (specifically, the adhesive R).
The optical disc formed in such a way includes a memo-plate but has a great capacity due to the double configuration of signaling sides thereby increasing memory capacity so that it is a so called xe2x80x9cDVD 9xe2x80x9d.
If greater capacity is required of the optical disc, the DVD 9 and the aforementioned second disc-shaped substrate (Specifically, UV Resin) are laminated by the adhesive to the second disc-shaped substrate to form DVD 14.
Among others, the step of peeling the first disc-shaped substrate 100 from the second disc-shaped substrate 200 is very important when quality is determined.
Conventionally, both surfaces of the disc-shaped substrates are sucked and pulled from each other by an adsorbent pad.
Notwithstanding, an extremely great force is required to separate them from each other to afford powerful force. This will necessitate great absorptive force, thereby requiring increased effort.
When separation is made, local force is applied to the portion as sucked which introduces defects through distortion of the disc-shaped substrate.
Further, problems arise from lack of uniformity of a surface as peeled off.
The present invention is provided to solve the aforementioned problems.
It is an object of the invention to provide a method and an apparatus for precisely peeling both of the disc-shaped substrates off by a simple device without requiring any greater separating force.
In view of the aforementioned problems, as a result of concentrated research thereon, such problem has been readily and precisely solved more than as expected by blowing gas between the disc-shaped substrates to separate them.
A first aspect of the invention resides in a method of pulling away upper and lower disc-shaped substrates from each other wherein the upper and lower disc-shaped substrates are laminated by the adhesive, and wherein gas is blown therebetween to peel the substrates away from each other.
A second aspect of the invention resides in the peeling off method wherein pulverized adhesive dust is exhausted from the periphery of the optical disc.
A third aspect of the invention resides in the method wherein gas is blown by a boss member inserted into a center hole in the optical disc.
A fourth aspect of the invention exists in the exfoliating method wherein pulverized adhesive dust is sucked by sucking means mounted on a holding table to suck pulverized adhesive dust.
A fifth aspect of the invention exists in the exfoliating apparatus which comprises a holding table adapted to carry an optical disc composed of upper and lower disc-shaped substrates and a boss provided centrally of the holding table to allow gas to blow between both of the disc-shaped substrates.
A sixth aspect of the invention resides in the exfoliating apparatus comprising suction means peripherally of the holding table to suck pulverized adhesive dust when the two disc-shaped substrates are peeled off from each other.
A seventh aspect of the invention resides in the exfoliating apparatus comprising a suction means which includes a suction groove so formed as to open circumferentially of the two disc-shaped substrates.
An eighth aspect of the invention exists in the exfoliating apparatus wherein the holding table is provided with a circular flange to receive gas exhausted from the circumference of the two disc-shaped substrates.
A ninth aspect of the invention exists in the exfoliating apparatus wherein the holding table is provided with sucking and holding means for sucking and holding the two disc-shaped substrates.
A tenth aspect of the invention resides in the exfoliating apparatus which comprises a holding table adapted to carry an optical disc composed of upper and lower disc-shaped substrates laminated to each other, a boss disposed centrally of the holding table allowing gas to blow between the disc-shaped substrates, and suction means peripherally of the holding table to suck pulverized adhesive dust when the two disc-shaped substrates are peeled off from each other.
The suction means is provided with a suction groove so formed as to correspond to the periphery of the two disc-shaped substrates, the holding table being provided with sucking and holding means for sucking and holding the two disc-shaped substrates.
According to this invention, it is possible to employ an exfoliating or peeling method adopted in combination with more than two arrangements selected from the aforementioned 1xcx9c4 and an exfoliating apparatus employed in combination with more than two arrangements selected from the aforementioned 5xcx9c10.
According to the exfoliating or peeling apparatus according to this invention, both of the disc-shaped substrates may be suitably separated from each other by simple means.
In accordance with the present invention, the two disc-shaped substrates may be readily and precisely peeled and exfoliated by simply blowing gas therebetween.
Conventionally, the disc-shaped substrates have been subjected to distortion, but never distorted to perform a uniform exfoliation when the latter is made.
Pulverized adhesive dust and the like may be sucked when exfoliation is made so that troublesome matter over mechanical equipment and the like may be eliminated.